1. Field of the Invention
The present invention relates to a hinge device in a portable terminal, and more particularly, to a device for fixing gear cams in a dual-hinge device that provides two hinge axes.
2. Description of the Related Art
A portable terminal typically refers to an information providing device such as a cellular phone, a smart phone, a smart pad, a laptop, a Web hard drive, etc. Portable terminals are categorized into a bar type, a folder type, and a sliding type according to their outward appearances. In addition, wearable-type portable terminals have also emerged, including a glasses type and a wrist type, for example.
Among the above types of portable terminals, a folder-type portable terminal is known which is provided with a hinge device that connects two housings in a rotatable manner. The hinge device is configured so as to provide one or two hinge axes. Accordingly, a single-hinge device or a dual-hinge device can be adopted for use in the portable terminal.
In general, when a hinge device as used in a folder-type portable terminal a cam unit (a driving cam and a driven cam) and an elastic member are typically included so that a stopping force may be applied to a rotating housing at a specific angle and the portable terminal may semi-automatically be opened or closed. This semi-automatic convenience is provided to the user as a result of a cam motion between the driving cam and the driven cam of the cam unit. To allow a user to conveniently open or close the portable terminal, a closing force should be applied continuously in a closed state, an opening force should be applied at or above a predetermined first angle, and a stopping force should be applied at a predetermined second angle.
An exemplary dual-hinge device for a portable terminal is disclosed in Korea Patent Publication No. 2011-34189, in Korea Patent Publication No. 2007-7942, and in U.S. Patent Publication No. 2007-54710.
With reference to FIGS. 1 to 5, the gear cam mounting mechanism of a conventional dual-hinge device will be described below.
Referring to FIGS. 1 and 2, a conventional dual-hinge device 70 includes first and second hinge units, thus providing two parallel hinge axes, that is, first and second hinge axes A1 and A2. A guide bushing 71 is installed at one side of the first and second hinge units and a Flexible Printed Circuit Board (FPCB) guide 72 is installed at the other side of the first and second hinge units. The first hinge unit includes a first gear cam 73, a first cam follower 74, and a first elastic member 75, whereas the second hinge unit includes a second gear cam 76, a second cam follower 77, and a second elastic member 78. As a rotational housing (not shown) rotates, the gear cams 73 and 76 rotate and the cam followers 74 and 77 move back and forth in a linear reciprocal motion along a respective one of a first hinge shaft S1 and a second hinge shaft S2, as a result of cam motion with the gear cams 73 and 76. Reference characters F1 and F2 denote top and bottom frames, respectively.
Referring to FIG. 3, because the first gear cam 73 is fixedly attached so as to surround the first hinge shaft S1, the first gear cam 73 rotates along with rotation of the rotational housing. A first locking member 80 formed on the first hinge shaft S1 b insert molding is inserted into the first gear cam 73, so as to provide the fixed attachment of the first hinge shaft S1 to the first gear cam 73. A locking protrusion 81 is extended from an outer surface of the first locking member 80 along the direction of the first hinge axis A1 and a locking groove (not shown) having height, width and length dimensions that correspond with the height, width and length dimensions of the locking protrusion 81 is formed in an inner surface of the first gear cam 73 along the direction of the first hinge axis A1, which locking groove allows the first locking protrusion 81 to be inserted therein. With this arrangement, when the first gear cam 73 is inserted by a press fit over the first locking member 80, the first gear cam 73 becomes locked to the first locking member 80 so that the first gear cam 73 can rotate along with rotation of the first hinge shaft S1.
Because the first locking protrusion 81 and the locking groove (not shown) are extended along the direction of the first hinge axis A1, the first gear cam 73 rotates along with a rotating motion made around the first hinge axis A1. The second gear cam 76 is also fixed by the same gear cam mounting mechanism of the first gear cam 73.
Referring to FIGS. 4 and 5, when the first and second gear cams 73 and 74 rotate in engagement with each other, their teeth areas are engaged with their non-teeth areas during the rotation.
As stated before, the locking members are insert-molded to the hinge shafts in the dual-hinge device having the above-described configuration. Because the portable terminal is prone to frequent impacts as a result of being dropped, the impacts are transferred to the dual-hinge device. As each impact is subsequently transferred to the hinge shafts to which the locking members are fixed by insert molding, the locking members and the gear cams are progressively deformed or damaged. Even more destructive is that the impact adversely affects the tilting function of the rotational housing.
In addition, the conventional dual-hinge device does not have an structure to prove a stopper function. Accordingly, in the event of excessive rotation, the engagement structure between the locking members and the gear cams is adversely affected, thereby damaging the locking members and the gear cams.
Thus, there exists a need for reinforcing the structural strength of the engagement structure between a locking member and a gear cam in a dual-hinge device of a portable terminal to withstand dropping impacts and excessive rotational forces applied to the dual-hinge device.